"The attempt to find any naturalistic property or relation with which noncircularly to identify 'mental reference' has come to be called the problem of 'psychosemantics.' ...
The first [approach] is the 'Causal-Historical' approach, in the spirit of Kripke ... and Putnam... , according to which a mental/brain item M refers to a thing X just in case X figures appropriately in M's etiology [etiology: 'assignment of a cause' - COD]. Practitioners of this approach cash the word 'appropriately' in any number of hopeful ways; any successful way will have to account for reference to non- existent things, no small task in itself and multiply hard given that one may not, on pain of circularity, invoke unexplicated propositional-attitude contents."
Lycan's Introducton to Part IV of Mind and Cognition, 2nd Ed. p. 196,7